Chemical sensors and biosensors have been utilized for detecting many species, from contaminants in air to the presence of particular DNA segments in blood samples or other samples. More recently, sensors utilizing nanostructures such as nanowires (NWs) and carbon nanotubes (CNTs) have been proposed. This has been described in detail in several papers such as in Kong et al., Science, vol. 287, pp. 622-625 (Jan. 28, 2000).
US 2005/0053525 describes sensor platforms and related methods of making such sensor platforms which comprise nanostructures such as nanowire sensor elements oriented substantially parallel with respect to a major surface of a substrate and having nanostructures, such as nanowires, which, in various embodiments, may have or may be formed to have an affinity for a corresponding analyte.
Furthermore chemical sensors have been described which are made of nanostructures which are functionalized or otherwise modified to become molecule-specific or species-specific sensors (see P. Qi et al., “Toward Large Arrays of Multiplex Functionalized Carbon Nanotube Sensors for Highly Sensitive and Selective Molecular Detection” Nano Lett., vol. 3, no. 3, pp. 347-51 (2003)).
Dai et al., “Carbon Nanotube Sensing,” U.S. patent application Ser. No. 10/175,026, filed on Jun. 18, 2002, now U.S. Patent Publ. No. US-2002-0179434 A1.
Unfortunately, although sensor devices comprising nanostructures are described and capabilities are evolving for the use of individual nanotubes in a sensor arrangement, a need exists for a more reliable vehicle or platform, or in other words a more reliable design to serve as a sensor. The above-described devices are not reliable because they have limited selectivity and limited sensitivity especially at low concentrations.